Technical Field of the Invention
The present invention relates to a sprocket. More particularly, the present invention relates to a sprocket formed from dissimilar materials, including a tooth member formed of ferrous material, and a circular disk, which is formed of a light metal and which supports the tooth member thereon.
Background Art
Conventionally, in a sprocket, a technique of connecting a circular disk with a tooth member by shrinkage fitting of a steel annular member having the tooth member on its periphery on the outer periphery of a circular disk of a light alloy such as aluminum, is known (for example, see Japanese Patent Literature JP-A No. S58-113597). According to JP-A No. S58-113597, it is possible to reduce weight by forming the circular disk with a light alloy, such as aluminum, while forming the tooth member with steel to ensure toughness and abrasion resistance.
However, in the above-described conventional sprocket, as the annular member having the tooth member and the circular disk are connected with a friction force by engagement of the shrinkage fitting, to generate a sufficient friction force by enlarging the area of the connected part, it is necessary to increase the plate thickness of the sprocket, and the weight reduction is limited.